Seasonal variation of solvent extractable organic compounds in the aerosols in Qingdao, China

The solvent extractable organic compounds in 22 seasonal total suspended particulate samples collected in Qingdao, China during June 2001-May 2002 were analyzed using gas chromatograph/mass-selective detector. Included in these samples were three from Asian dust episodes. The characteristics and abundance of the n-alkanes, polycyclic aromatic hydrocarbons and fatty acids were determined. Distinct seasonal variations were detected in the Qingdao samples. The n-alkanes were found to contain substantial amounts of petroleum residues (56.0% in summer, 64.4% in fall, 77.6% in spring and 81.5% in winter). The winter polycyclic aromatic hydrocarbons (PAHs) were from combustion sources including coal burning for space-heating and the average PAH yield was 14.4 times higher than that in summer. The <C₂₀ homologues, mainly from kitchen emissions and microbial origins, dominated the fatty acid fraction and they constituted 72.8%, 81.9%, 86.9% and 92.6% of the winter, spring, fall and summer samples, respectively. The three Asian dust episode samples possessed characteristics typical of long-distance transport samples with Cmax at C₂₉ and C₃₁ and relatively high carbon preference index values (l.85-2.37) for the alkanes, and high plant wax content (38.7-45.5%) in the fatty acids even though the total yields were not substantially larger.